Artykuł
11/18/2011

Strings.FormatDateTime Method

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Returns a string expression representing a date/time value.

Namespace: Microsoft.VisualBasic
Assembly: Microsoft.VisualBasic (in Microsoft.VisualBasic.dll)

Syntax

'Declaration
Public Shared Function FormatDateTime ( _
    Expression As DateTime, _
    NamedFormat As DateFormat _
) As String

public static string FormatDateTime(
    DateTime Expression,
    DateFormat NamedFormat
)

Parameters

Expression
Type: System.DateTime
Required. Date expression to be formatted.

NamedFormat
Type: Microsoft.VisualBasic.DateFormat
Optional. Numeric value that indicates the date/time format used. If omitted, DateFormat.GeneralDate is used.

Return Value

Type: System.String
Returns a string expression representing a date/time value.

Remarks

The Date data type always contains both date and time information. For purposes of type conversion, Visual Basic considers 1/1/1 (January 1 of the year 1) to be a neutral value for the date, and 00:00:00 (midnight) to be a neutral value for the time. If you format a Date value as a date/time string, FormatDateTime does not include neutral values in the resulting string. For example, if you convert #1/1/0001 9:30:00# to a string, the result is "9:30:00 AM"; the date information is suppressed. However, the date information is still present in the original Date value and can be recovered with functions such as DatePart.

Note:
If you pass the Expression argument as a String literal, FormatDateTime interprets it according to the CurrentCulture setting of your application. However, if you pass it as a Date literal, use the format #mm/dd/yyyy#, because FormatDateTime always interprets a Date literal according to the English (US) culture. This is necessary because, if an application is developed and coded using Date literals from one culture, but is then executed on a platform with a different culture, the Date literals could be parsed incorrectly.

If you pass the Expression argument as a String literal, FormatDateTime interprets it according to the CurrentCulture setting of your application. However, if you pass it as a Date literal, use the format #mm/dd/yyyy#, because FormatDateTime always interprets a Date literal according to the English (US) culture. This is necessary because, if an application is developed and coded using Date literals from one culture, but is then executed on a platform with a different culture, the Date literals could be parsed incorrectly.

The NamedFormat argument has the following settings.

Constant	Description
DateFormat.GeneralDate	Display a date and/or time. Display a date part as a short date. If there is a time part, display it as a long time. If present, both parts display.
DateFormat.LongDate	Display a date using the long date format specified in your computer's regional settings.
DateFormat.ShortDate	Display a date using the short date format specified in your computer's regional settings.
DateFormat.LongTime	Display a time using the time format specified in your computer's regional settings.
DateFormat.ShortTime	Display a time using the 24-hour format (hh:mm).

Examples

This example demonstrates the use of the FormatDateTime function.

' English (US) format.
Dim TestDate As DateTime = #3/12/1999#

' FormatDateTime returns "Friday, March 12, 1999".
' The time information is neutral (00:00:00) and therefore suppressed.
Dim TestString As String = FormatDateTime(TestDate, DateFormat.LongDate)

Version Information

Silverlight

Supported in: 5, 4, 3

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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